Re: [PATCH] x86: Accelerate copy_page with non-temporal in X86
on 2021/4/13 22:53, Borislav Petkov wrote: > I thought "should be better" too last time when I measured rep; movs vs > NT stores but actual measurements showed no real difference. Mabye the NT stores make difference when store to slow dimms, like the persistent memory I just tested. Also, it likely reduces unnecessary cache load and flush, and benifits the running processes which have data cached. -- Best wishes Kemeng Shi
Re: Re: [PATCH] x86: Accelerate copy_page with non-temporal in X86
On Tue, Apr 13, 2021 at 08:54:55PM +0800, Kemeng Shi wrote: > Yes. And NT stores should be better for copy_page especially copying a lot > of pages as only partial memory of copied page will be access recently. I thought "should be better" too last time when I measured rep; movs vs NT stores but actual measurements showed no real difference. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
Re: [PATCH] x86: Accelerate copy_page with non-temporal in X86
+ linux-nvdimm Original mail at https://lkml.kernel.org/r/3f28adee-8214-fa8e-b368-eaf8b1934...@huawei.com On Tue, Apr 13, 2021 at 02:25:58PM +0800, Kemeng Shi wrote: > I'm using AEP with dax_kmem drvier, and AEP is export as a NUMA node in What is AEP? > my system. I will move cold pages from DRAM node to AEP node with > move_pages system call. With old "rep movsq', it costs 2030ms to move > 1 GB pages. With "movnti", it only cost about 890ms to move 1GB pages. So there's __copy_user_nocache() which does NT stores. > - ALTERNATIVE "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD > + ALTERNATIVE_2 "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD, \ > + "jmp copy_page_nt", X86_FEATURE_XMM2 This makes every machine which has sse2 do NT stores now. Which means *every* machine practically. The folks on linux-nvdimm@ should be able to give you a better idea what to do. HTH. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
